Tank for aqueous electrolysis



June 13, 1950 J. ANDRE 2,511,686 TANK FOR AQUEOUS ELECTROLYSIS FiledApril 30, 1948 r s Sheets-Sheet 1 In venfor- June 13, 1950 J ANDRE2,511,686

TANK FOR AQUEOUS ELECTROLYSIS Filed April 30, 1948 a 3 Sheets-Sheet ZJune 13, 1950 J. ANDRE TANK FOR AQUEOUS ELECTROLYSIS 3 Sheets-Sheet 3Filed April 30, 1948 .271 Veda (Liv/20% 'w Patented June 13, 1950 TANKFOR AQUEOUS ELECTROLYSIS Jean Andr, Paris, France, assignor to Compagniede Produits Chimiques et Electrometallur- ,giques Alais, Froges etCamargue, Paris, France,

a corporation of France Application April 30, 1948, Serial No. 24,291

In France May 14, 1947 3 Claims.

The present invention relates to electrolysis tanks for aqueoussolutions and more especially alkali chlorates and perchlorates. Itsobjects is the provision of such a tank arrangement wherein thedistribution of the electric current among the various active poleelements is as uniform as possible, this leading to a more highlyuniform wear on the anode elements.

According to a feature of the invention the positive elements in thetank are comprised of spaced strips of graphite fitted at each endthereof in graphite bars which form potential distributors and placed atthe bottom of the tank, current being led to said bars throughsubstantially vertical conductor members.

This arrangement makes it possible to construct independent andremovable anode pole units adapted to be mechanically prefabricated andfacilitates the construction of electrolysis units having as high acurrent capacity as may be desired, through a simple juxtaposition ofsaid pole units in parallel relationship within a common tankpermanently installed in the electrolysis plant. The arrangement furthermakes it possible quickly to remove a used or worn out anode group andreplace it witha fresh one.

According to a further feature of the invention the cathode elements areso arranged as to permit of their being cooled and thereby to make itpossible to cool the electrolyser. rangement is found to be particularlydesirable especially in connection with the electrolysis of alkalichlorides for the manufacture of chlorates and perchlorates, inasmuch asit makes it possible to maintain at a low and uniform temperature thebody of the cathode elements themselves in graphitic anodeelectrolysers, and thereby in a very great measure to increase thecurrent density over the anode elements without incurring the danger ofa breakdown or excessive wear on said elements.

In practice said arrangement makes it possible to double the maximumcurrent density heretofore considered permissible without provision ofany cooling means other than thegeneral .coolattained where the cathodeelements are refrigerated with cool water.

Other features and advantages of the invention will appear from 'theensuing description Such arwhich relates to some forms of embodimentthereof given by way of example. In the description reference is made tothe accompanying drawing wherein:

Fig. 1 is a View in vertical cross section of a tank according to theinvention.

Fig. 2 is a view in vertical cross-section on a plane transverse to theforegoing figure.

Fig. 3 is a detailed view of the mounting of the anode elements.

Fig. 4. is a detailed view of an anode plate or strip.

Fig. 5 shows another embodiment of a multielement block or brick used asa support for the anode strips.

Fig. 6 is a view drawn to a larger scale of an end of said brick.

Fig. 6b shows a modification.

Fig. 7 is a detailed showing of a conductive member for leading currentto the bricks.

Fig. 8 shows the manner in which said current conveying members aremounted.

Fig. 9 is a detailed view of a modification of the current conveyingmeans for the anode elements.

The tank I is made of welded steel sheeting or cast iron. The cathodeassembly or bundle is provided in the form of a plurality of tubes 2 offlattened cross-section which in the example shown are welded inparallel spaced relationship with each other to the oppositelongitudinally extending walls of the tank, or else they may be embeddedon casting in said walls where the latter of cast iron. The tubes atboth their ends open outwardly of the tank.

' tween the pole surfaces.

The current from the anodes is divided among .the cathode strips andflows towards the side walls of the tank. through the tubes 2.Connections 4 are appropriately spaced along the longitudinal walls ofthe tank to draw 01f said current. Moreover in order to facilitate thecurrent distributween the connections 4.

Cooling of the electr'olyser isefiected by the cathodes themselves whichform a radiating unit, by means of a forced flow of water circulatedthrough the tubes 2 of the bundle. For that purpose both ends of thetubes 2 are made to issue into water jackets or headers 5v and 6provided with baille means therein. Pressure water is conveyed throughan inlet pipe I to the tank and is discharged through an outlet pipe 8.

The active portion of the positive unit or bundle comprises a pluralityof graphite strips 9 arranged in parallel spaced relationship andmaintained in such condition by being fitted or inserted in a pair ofgraphite blocks or bricks ill extending parallel with each other and atright angles with the strip 9. The opposite ends, II. and. i2 of eachstrip are machined to the form of a wedge having a predetermined angleof taper. Both bricks l0 comprise slots l3 therein formed to the sameangle of taper. The Whole assembly s m unt s hown in s- Electric currentis conveyed to the graphite bricks, It through graphite rods [atinserted by means of a tapered connection into the bricks.

The Whole arrangement forms an undeformable unitary pole assembly whichis easy to handle. This assembly is lowered into the tank in such a waythat the raphite strips 9 will alternate with the cathode strips 3placed opposite thereto as particularly shown in Fig. 2.

The aboye arrangement makes it possible to immerse the active portionsof the bundle as deep as desired under the surface level of the bath,

I thus providing the possibility of increasing the Faraday efiiciencyfactor of the system.

Supports 15 of dielectric material as narrow "as practicable in theirtransverse dimension enable the assembly thus constructed to rest uponthe tubes 2 while providing the necessary clearance for free unitaryexpansion of the strips.

The bricks ID are encased in a casing [6 of ebonite or any othersuitable dielectric material impervious to the solution in operation.Said casing prevents a. direct iiow of current as between the bricks HIand the adjacent negative elements. ing current to the bricks areencased throughout Likewise the rods l4v used for leadflatparalellopipedic blocks of graphite assembled with each other so as toform the brick of the desired initial shape. A metal rod which may bemade of steel extends through a central aperture throughout the entirebrick longitudinally thereof and provides for the possibility of firmlyclamping all of its elements together through the use of clamping platesand rubber members. Said metal clamping rod and the'related metalbearing members should not participate in the electrolyte process. Theyare completely insulated from the graphite structure which is at thepositive terminal and are directly connected with the negative terminalthrough a connectionmade of a metal similar thereto in character such asiron.

The system is so arranged that the path of loss between the negativemetallic portion and the adjacent positive graphite elements will belong enough to avert the occurrence of any parasitic electrolytic sideefiects. It should be observed however that in practice such parasiticelectrolytic side effects would not actually be very injurious, exceptfor slow gradual wear of the thicker graphite parts. They would simplycause both parts to play a similar function to that of the activeelements in the remainder of the assembly.

However, for considerations involving the evolution of gas, among otherreasons, it is desirable to avert the production of such effects withinthe central bore in the bricks and for this reason the specific mountingarrangements to be described hereinafter by way of example are provided.

As concerns the downward positive current leads into the depth of theelectrolysis bath, rather than usingas in the foregoing arrangementsgraphite rods fitted through a tapered connection paralellopipedicgraphite blocks of ordinary form are used, that is blocks that do notpossess any particularly great mechanical strength and the ends of whichare cut to the shape of paralellopipedic teeth fitted into the compositebrick assembly thereby both imparting mechanical rigidity to theassembly and providing an excellent electric contact for thedistribution of current into the brick.

In the examples shown the graphite plates comprising the brick are oftwo different types 30 and 3! which difi'er as to thickness. The plates3t. which are the thicker ones form the, teeth of the general mountingassembly, while the plates 3| define the gaps therebetween. All of theplates are formed with a central bore 32. Said plates assembled injuxtaposed relation may bemounted in any one of various ways and inparticular according to the arrangements shown.

In the arrangement shown in Fig. 6 a tube 33 made of a semi fiex ibl'edielectric substance'chemi'cally impervious to the electrolysissolutions, for instance plasticized polyvinyl chloride is insertedthrough the general longitudinal bore of the asrod 38, extends throughthe entire arrangement.

, Said rod is preliminarily coated with a coat of polyvinyl chloridevarnish or any other suitable dielectric varnish impervious to chemicalattack from the electrolyte solution. Said steel clamping rod is formedwith screw threads at both ends thereof and a nut 35 firmly clamps thewhole assembly against each of the washers member 42 serving to. conveycurrent thereto.

The lowermost end of said current conveying member 42 (Figs. 5, 7 and8') 1s machined so as to form teeth 43 (Fig. 7) said teeth also beingformed with a central bore which thus extends all along the brickthroughout its entire length. Insertion is effected as shown in detailin Fig. 8, the teeth 43 of the member 42' taking the place of the plates3| at this point.

After the assembly has been suitably clamped the composite brick thusformed may be milled, the milled portions occurring accurately oppositeto the plates 4|. It'will be understood that the positive graphitecurrent leads 42 may of course be machined to any other suitable form,and the connections therewith may be accomplished in any appropriatemanner.

A modification of a mounting assembly is shown in Fig. 62).

According to this modification, the inner dielectric tube 33 is a tubemade of a hard dielectric substance such as glass, ceramic material,hard polyvinyl chloride and the like. Such substance, althoughconsidered to be more fragile than that of which is made the tube in thepreviously described arrangement, has the advantage however of showingless tendency to be modified with time and is less liable to haveobjectionable cracks or fissures appear therein. In order to mount ithowever it is necessary to modify the ends in the manner described. Theresilient bearing-washer 34 and the ebonite coated steel clamp plate 35should be formed with a larger recess than in the previously describeddevice so as to enable the end of the tube 33 to pass therethrough; inorder to increase the length of the loss path, the ebonite-coated steelclamp plate 35 is provided with increased thickness. In other respectsthe mounting assembly is identical with the one described hereinabove.

Fig. 9 shows a modified conductive rod for leading current into tankshaving a high anode current density. To avoid an excessive voltage dropthrough the rod, the latter is provided hollow and within the recess I8therein there is inserted a copper rod [9 immersed in a mass of mercury.The graphite forming the rod 14 is specially impregnated to ensure itsimperviousness to the liquid of the surrounding bath.

It is essential that both tapers II and I2 of the strip 9 be identical,their opposite pairs of faces as seen from a common side of the stripnot only being parallel but also coplanar. This condition is a requisitein order that the insertion of the potential distributing member intothe bricks II) should not create any abnormal stress in the teeth ofsaid bricks and moreover in order that the positioning of each strip 9of the anode bundle with respect to the negative bundle should beaccurately defined.

It will of course be understood that the present invention is notrestricted to the specific forms of embodiment shown and described andthat it may be carried out in a large number of modified forms.

What I claim is:

1. An electrolysis tank which comprises in combination a container, acathodic structure including a plurality of parallel tubes extendingacross the lower inner part of the container and adapted to conductelectrolysis current to the side walls of said container, a plurality ofperforate metallic plates in parallel spaced relationship, each of saidplates being secured along its bottom longitudinal edge with one of saidtubes, means to circulate a cooling fluid through said tubes, electricinsulators carried by said tubes near the ends thereof, and an anodicstructure which comprises a pair of oppositely arranged parallel blocksextending above said tubes at right angles thereto and set upon saidinsulators within said container, and a plurality of parallel verticalspaced anodic strips, extending across said blocks in alternatingrelationship with said plates and having their opposite ends inserted inrecesses formed in said blocks, and vertical conducting members, adaptedto convey positive current, fitted into the top face of said blocks.

2. An electrolysis tank, which comprises in combination a container, afixed cathodic structure comprising a plurality of parallel tubespassing through two opposite side walls of the container and through itslower inner part, and electrically connected with the side walls of thecontainer, electric insulators carried by said tubes near the endsthereof, means for circulating a cooling through said tubes, a set ofparallel spaced perforated metal plates, one edge of each of said platesbeing welded to one of said tubes, and a movable unitary anodicstructure, which comprises a pair of oppositely arranged, parallelspaced blocks and a plurality of parallel vertical spaced anodic stripsextending across said blocks and inserted at their opposite ends intorecesses of said blocks, vertical conducting members adapted to conveypositive current fitted into the top face of said blocks, the entireunitary anodic structure being arranged in said container at apredetermined depth therein in such a way that said blocks are set uponsaid tubes at right angles thereto through the electric insulatorscarried by the same, the said metallic plates being positioned in spacedalternating relationship with said anodic strips.

3. An electrolysis tank as claimed in claim 1, in which each of saidblocks comprises a number of juxtaposed strip shaped elements clampedtogether forming a plurality of parallel vertical recesses on one sideof the block.

JEAN ANDRE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 507,374 Lyte Oct. 24, 1893674,927 Mauran May 28, 1901 1,053,266 Barstow Feb. 18, 1913 1,359,716 LeSueur Nov. 23, 1920 2,177,453 Donald Oct. 24, 1939 FOREIGN PATENTSNumber Country Date 13,690 Great Britain of 1896 118 Great Britain of1902 121,460 Great Britain June 19, 1919 444,709 Great Britain Nov. 23,1920

